Muffler of internal combustion engines



Feb.-l5 1938. K. KATO MUFFLER OF INTERNAL COMBUSTION ENGINES Filed Dec. 27, 1934 x. 1 1.. kufi u Patented Feb. 15, 1938 MUFFLER OF INTERNAL COMBUSTION ENG Kihachi Kato, Tokyo, Japan,

INES

assignmof seventenths to Gonsahuro Ishibashi, Tokyo, Japan Application December 27, 1934; Serial No. 759,334 In Japan December 27, 1933 1 Claim.

The present invention relates to an improved muflier which is designedto receive. the discharge gases from internal combustion engines and the like and to discharge them noiselessly, the muffler 5 comprising an elongated hollow cylindrical member with a corrugated helical plate therein.

The principal object of my invention is to provide a corrugated helical plate which produces an interference with high sound waves to extinguish the noise of high frequency sound by its unevenness of corrugations, and which reduces the pressure of the exhaust gas by its whirling motion to extinguish the noise of low frequency sound, and, Oflering minimum resistance to the passage of exhaust gas, avoids the accumulation of back pressure in the mufller, which causes a serious loss of power.

A further object of the invention is to provide an apparatus in which the parts thereof. are closely assembled and combined, thereby taking up a minimum amount of space and rendering the device especially applicable for operation in connection with automobiles.

A still further object of the invention is to provide a corrugated helical plate which is easily taken out from the cylindrical hollow chamber for removing all foreign matter from said chainber and corrugated spiral plate.

In prior art engines, loud explosions take place when the exhaust valve is opened directly to the atmosphere, the reason being that the pressure in the cylinder is much higher than atmospheric pressure and that therefore a sudden discharge from one to the other will produce a loud report. The more suddenly this charge takes place and the greater the difference in pressure, the more violent is the explosion.

In accordance with the present invention, means are provided to decrease the pressure and to cause the exhaust gas to flow uniformly before it escapes into the atmosphere. The construction and arrangement of the various parts of the apparatus will be brought out more in detail in the description to follow, which, for a clear understanding of the invention, should be considered in connection with the accompanying drawing forming a part thereof, and wherein are disclosed, for the purpose of illustration, convenient and satisfactory embodiments of the invention. It is to be noted in this connection that minor changes in the construction and arrangement of the parts may be made without departing from the spirit of the invention or the principle of operation of the various parts.

In the drawing:

Figure 1 is a section through a muffler constructed in accordance with the principles of the present'invention;

Figure 2 is a back view of this muffler;

Figure 3 is a section alongthe line A B of Figure 1; and

Figure 51 shows the muiller ina front view. The drawing shows a central pipe i connected to the exhaust pipe of the engine. A corrugated helical plate 2 is inserted in the plate I, said plate consisting of a central shaft 3 around which a corrugated iron band or plate is wound. The corrugations on. this band are concentrated at the central portions thereof, the peripheral portions being substantially smooth. A chamber. 8 surrounds the central pipe I and is provided with several holes 1 which are situated at the front side 'of the chamber.- The gas passes through these holes from the chamber 6 to an outer chamber 8 which concentrically surrounds the middle chamber 5. The device is also pro vided with a cover 4 which closes the outlet of the central pipe I and which carries oneend of the central shaft 3. The cover 4 is provided with several long channels 5-used for breaking up the gas as it flows into the air.

The exhaust gas coming from the exhaust pipe enters the central pipe I and is caused to carry out a revolving motion in the passages formed by the corrugated helical plate 2. The outer diameters of the helical plate decrease continuously on the front side to reduce the impact pressure to which the plate is subjected.

The revolving gas in the central pipe reaches the partition 8 and flows through comparatively large holes l0 into the middle compartment 8.

The gas expands in this compartment and flows through the forward end of the device, passing through the holes i into the outer chamber '8, The gas flowing rearward in the outer chamber 8 passes through several holes ll back into the central pipe I, which contains a second corrugated helical plate or band 2'. Finally, the gas is discharged into the atmosphere through the channel holes 5.

The exhaust gas having a high pressure at the entrance to this muiiier will strike the corrugated helical plate 2, but this impact pressure will be reduced greatly due to the fact that the plate is small in diameter at the point of entry and is inclined to the direction of flow of the gas. Consequently, the back pressure of the exhaust gas will be greatly reduced. In the course of the backward flow of the gas, it carries out a whirling or revolving motion and thereby its revolving inertia is increased, so that the high pressure gas will be mixed substantially uniformly with the low pressure gas, the pressure of which approximates that of the atmosphere. Thus, the high frequency sound waves comprising 3000 to 10,000 cycles per second and which emanate from the exhaust manifold are reduced by their impact against the corrugations of the helical band and frequency waves comprising 50 to 440 cycles per second, which emanate from the outlet of the muffler, the reduciton resulting in substantial ex tinction of the noise. Contrary to the general mix with the low theory, therefore, according to the invention the noise may be extinguished without increasing the back pressure of the exhaust gas.

I claim:

An exhaust mufiier comprising an elongated 5 cylindrical tube, a rod in said elongated tube, a

helical plate, around said rotatable rod, said.

helical plate being centrally corrugated adjacent said rod and having a substantially smooth periphery, whereby the high frequency sound waves emanating from the exhaust manifold are re duced and the noise extinguished.

KIHACHI KATO. 

